Porous films and bodies with enhanced mechanical strength

ABSTRACT

This invention provides a process for making a polyfunctional starburst-shaped fullerene derivative for use as a matrix-reinforcing agent for mesoporous and other porous materials. This invention can include the formation of a highly soluble example of such a derivative from a fullerene and a bifunctional coupling agent. A solution of said agent can be delivered to the surface of a porous solid during, or after, the solids formation. Porous films and bodies containing such a matrix-reinforcing agent can exhibit improved mechanical properties, and can be produced using equipment and techniques common and available to those skilled in the art of porous materials preparations.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.10/906,534, filed Feb. 24, 2005, the disclosure of which is incorporatedby reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure relates generally to porous materials, and moreparticularly to producing oxides and other porous or partly-porouscompositions and structures having enhanced mechanical strength.

2. Related Art

Porous materials with feature sizes expressible roughly in terms ofnanometers or smaller comprise an important class of materials useful inan ever-increasing range of applications. Chief among these applicationsare membranes (U.S. Pat. No. 6,536,604, Brinker, et al.), sensors (U.S.Pat. No. 5,885,843, Ayers and Hunt), display devices (U.S. Pat. No.6,329,748, Kastalsky, et al.), and, notably, microelectronic devices,where such materials show promise as low dielectric constant materials(U.S. Pat. No. 5,789,819, Gnade, et al.). However, many seemingly usefulmaterials do not exhibit the necessary mechanical strength required bythe aforementioned applications. This results from the fact that manydesirable properties, such as high permeability or low dielectricconstant are maximized only when the material possesses a relativelyhigh void fraction, or porosity. High porosity generally leads tolower-strength materials, relative to fully dense materials of similarcompositions, and typically precludes the use of such materials inpractice. Increasing the mechanical strength of porous materials is mosteasily accomplished by simply lowering their porosity. However, thisoften counteracts many of the beneficial properties of higher porosityanalogs. Therefore there is an important need for materials with afavorable combination of relatively high porosity and good mechanicalproperties.

Common terms used in the art, and also used herein, to describe themicrostructure of porous materials are microporous, referring to amaterial possessing pores between 0.3 and 1.0 nm in diameter,mesoporous, for pores between 1.0 and 50 nm, and macroporous for poresgreater than 50 nm. Porosity refers to the volume fraction of thematerial occupied by a fluid or gaseous phase, and is commonly reportedas a percentage of the total volume.

Many commonly occurring mesoporous materials exhibit a microstructureformed by the linking of small (1-10 nm diameter) particles into athree-dimensional network spatially conterminous with an interconnectingopen-pore network. Such structures are commonly formed by sol-gelprocessing, a technique well-known to those skilled in the art. Theparticles mentioned above may occur in a wide variety of shapes,including spheres, rods, platelets, polygons, as well as irregularshapes. The points of contact between these particles result in materialdeficiencies that lead to weaknesses in their bulk structures.

There exist few methods which are effective in strengthening the solidnetwork of a mesoporous material without adversely affecting itsdesirable properties. One such method is Ostwald ripening. See Brinkerand Scherer, Sol-Gel Science: The Physics and Chemistry of Sol-GelProcessing, Academic Press, Chapter 3.3 (1989). In that process, withincertain pH ranges, material is dissolved from solid surfaces with apositive (concave) radius of curvature into the surrounding pore fluid,and redeposited on surfaces with a negative (convex) radius ofcurvature. However, this process is slow. Additionally, as the materialwhich serves to reinforce weak points in the network must be obtained atthe sacrifice of other parts of the same network, there is a finiteamount of strength improvements that may be obtained in this way.

Another approach has been demonstrated by Haereid, et al. (Journal ofNon-Crystalline Solids, vol. 186, pages 96-103 (1995)). Haereid, et al.strengthened a wet silica gel by reinforcement of the solid networkusing a similar alkoxide precursor to that which formed the originalgel. Although this approach may toughen the solid network, it does so bydecreasing the porosity of the material significantly. This may haveundesired side effects, such as where decreasing the porosity of amixture by adding silica would have an undesirable effect on themixture's overall dielectric constant.

Therefore, there remains a distinct need for materials and procedurescapable of significantly enhancing the physical and mechanicalproperties of porous solid networks without significantly decreasing thematerial's porosity, or otherwise adversely affecting its desirableproperties.

It should be noted that useful materials such as fullerenes have founduses in the general field of porous materials, for example as asacrificial templating material (U.S. Pat. No. 5,744,399, Rostoker, etal.), or as blocking groups for preventing material shrinkage (U.S. Pat.No. 6,277,766, Ayers). However, such materials have had limited use dueto their poor solubility and/or (historical) high cost.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present disclosure, a polyfunctional,starburst-shaped molecule is synthesized which serves as amatrix-reinforcing agent for any of several compositions of inorganicporous materials, e.g. silica and/or other inorganic oxides. Thematrix-reinforcing material of the present invention contains a centralcore comprised of a fullerene, and three or more radial arms distributedsymmetrically around the core. The radial arms of this aspect of thepresent invention are each terminated by a reactive group capable ofcovalently bonding to the matrix material to be strengthened. These armsserve as coupling and crosslinking agents, and in so doing impart to thematrix material the desired strength improvements.

In another aspect, fullerene derivatives may be produced by a methoddescribed below that includes a step of dissolving a fullerene (e.g. C₆₀and C₇₀) into one or more organic solvents such as an alkane, a ketone,an aromatic, or an alcohol.

In another aspect, the above-mentioned matrix-reinforcing material iscombined with the matrix material of a sol-gel process while thelatter's three-dimensional solid network is still in a process offormation. This allows the matrix-reinforcing material to localize atthe contact points of the coalescing particles, thereby imparting a verylarge strength enhancement for a given amount of material.

In further aspect, the terminal reactive groups of thematrix-reinforcing material are selected such that the rate of reactionat that site is substantially less than the similar reactions in processat the surface of the solid matrix. This aids in the preferredlocalization of the matrix-reinforcing material at the primary particlecontact points.

In a further aspect, the matrix-reinforcing material is added to thesolid matrix after the formation of said matrix has been completed. Thisis accomplished by contacting a solution of the matrix-reinforcingmaterial with a fluid-filled matrix material and allowing theinfiltration of the matrix-reinforcing material into the pore fluid ofthe matrix material. The matrix-reinforcing material is therebydeposited onto a majority of the exposed solid surface of the matrixmaterial. This is especially desirable if a chemical modification of thesolid surface is sought in addition to mechanical enhancement. Theporous films and/or bodies so prepared can be dried using methods commonin the art, and thermally treated to complete the bonding of thematrix-reinforcing material to the solid surface of the matrix, as wellto affect the crosslinking of adjacent matrix-reinforcing molecules.

Further features and benefits of various aspects and embodiments of thepresent invention will become apparent in light of the followingdrawings and their accompanying detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The invention is to be explained in more detail below based on aspectsdepicted in the following figures where:

FIG. 1 shows a portion of a matrix-reinforcing molecule of the presentdisclosure.

FIG. 2A-2B shows a representation of the shapes and relative scales oflinked, 6-nm diameter solid particles, of a typical porous matrix, asformed by sol-gel processing, and with the addition of a preferredamount of the matrix-reinforcing molecules.

FIG. 3 gives a schematic representation of the process steps involved inthe methods of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

A matrix-reinforcing material of the present invention is well-suitedfor enhancing the physical and mechanical properties of mesoporousmaterials. In one embodiment, a material or structure of the presentinvention comprises a central fullerene core symmetrically derivatizedby three or more bifunctional coupling agents; the molecules prepared inthis way possessing the ability to bind to the surface of a desiredporous inorganic or oxide material, the ability to crosslink with oneanother, and excellent thermal stability. The matrix-reinforcingmolecules prepared according to the present invention are of a size thatallows them to fill the smallest pores and voids of a typical mesoporousmaterial. The present disclosure also teaches method embodimentssuitable for delivering said matrix-reinforcing molecules to the desiredportions of a porous solid network, depositing them there, andperforming a final curing step to increase the mechanical properties ofsaid porous solid. Any preparative route that produces a polyfunctionalfullerene derivative, where the fullerene is symmetrically surrounded bymultiple arms each terminated by a reactive group may be used, howeverthe preferred method involves the use of a bifunctional coupling agentto form the arms that contains, at one end an amine group and at theopposite and a metal or metalloid alkoxide. However, any coupling agentwhich is capable of reacting with both a fullerene and the surface ofthe porous solid may be used.

According to another embodiment, the fullerene core of thematrix-reinforcing molecules primarily include one or more of thefollowing: C₆₀, C₇₀, C₇₂, C₇₄, C₇₆, C₇₈, C₈₄, C₉₆, and higher analoguesup to, and beyond, C₁₈₄ or mixtures thereof. Commercially availablemixtures of C₆₀ and C₇₀, commonly know as Fullerite, fullerene extract,or fullerene soot may also be employed in various embodiments of thepresent invention.

Many possible compounds that are well-suited to form the reactive armsof the matrix-reinforcing molecules are readily available. Preferredcompounds and structures of the present invention generally includethree primary components: a terminal group that reacts with fullerenes,a linear organic spacer, and an opposing terminal group capable ofreacting with the surface of the desired porous solid. The number ofarms in each matrix-reinforcing molecule may vary. In preferredembodiments, there may be about 4-7 (e.g., 6) arms per core.

The terminal group, configured to couple the arms to the fullerene core,can include a primary or secondary amine. Amines are known to thoseskilled in the art to react with fullerenes in a facile manner.Generally this occurs by a nucleophilic addition reaction across one ofthe many delocalized bonds of the fullerene cage. Anywhere from one totwelve amine molecules may be added to a single C₆₀ molecule, the actualnumber depending largely on their stearic bulk, with the most commonnumber of additions being six. Other reactive groups, especially othernucleophiles, may be used in addition. These optionally include mixturescontaining azides, dienes, and/or carbanions. However, any reactivegroup which may be found to react effectively with fullerenes may beemployed according to the present invention.

The organic-spacer portion of the coupling agent may contain an alkylchain, a polyether chain, a polyunsaturated alkyl chain, and/or anamine-containing alkyl chain. The chain length of the spacer will bedetermined in part by the desired mechanical properties of the final,reinforced porous material. Shorter chain lengths, for example 3 or 4carbon units long, will provide greater rigidity, while longer chains of10-20 carbon units will result in greater flexibility. In the preferredaspect of the present invention said organic spacer is an alkyl chain3-20 carbon units long, or more preferably 3-7 carbon units long.However, when greater rigidity is desirable, said alkyl chain mayinclude one or more heteroatomic groups, such as ether groups or aminogroups, or one or more rigid components, including, but not limited to,alkynyl-segments, aryl-segments, or other cyclic segments.

The coupling agent is used for binding the matrix-reinforcing materialto the solid surface of the porous material. This may be comprised ofany of several common functionalities, however as porous inorganicoxides comprise the most common class of porous material currently usedin practice, the preferred terminal group according to the presentinvention is a metal- or metalloid-alkoxide. Alkoxides are known in theart to react upon hydrolysis with the chemically similar surfaces ofsolid oxides. Any one of numerous possible alkoxide groups may be usedaccording to the present invention, including, not limited to, —Si(OR)₃,—Ge(OR)₃—Ti(OR)₃, —Zr(OR)₃, —Sn(OR)₃, —Al(OR)₂, —B(OR)₂. However, assilica is the most common porous oxide in use today, the preferredcomposition of the terminal group is —Si(OR)₃.

The following are non-limiting examples of suitable, commerciallyavailable coupling agents useful in many embodiments of the presentinvention: 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,2-aminoethyl-3-aminopropyltrimethoxysilane,2-aminoethyl-3-aminopropyltriethoxysilane,diethylenetriaminopropyltrimethoxysilane,hexanediaminomethyltriethoxysilane, 11-aminoundecyltriethoxysilane.However, it will be understood that many additional compounds may beused in accord with the processes of the present invention.

A matrix-reinforcing material can be prepared by combining a desiredamount of the selected fullerene core with a large excess (i.e. severaltimes larger, by weight) of a selected coupling agent. Initially, insome embodiments, the fullerene is substantially insoluble in thecoupling agent and is present as a fine black suspension. Reaction ofthe amine group of the coupling agent with the fullerene occurs readilyat ambient temperature; however, heating the mixture to 50-60° C. orhotter allows the reaction to proceed at a more desirable rate. As thereaction proceeds, the partially derivatized fullerenes exhibitincreased solubility in the coupling agent and the mixture exists as adark brown solution. After approximately 18 hours, the formation of thestarburst-shaped matrix-reinforcing compound is complete and in mostinstances with a maximum number of coupling agents, typically about six,being added to the fullerene core. A large portion of an unreactedcoupling agent is removed using vacuum-distillation and is recovered foruse in future preparations. This leaves a deep brown-black residuecontaining the matrix-reinforcing compound. An example of such acompound, derived from C₆₀ and 6-aminohexyltriethoxysilane is shown inFIG. 1

An advantageous aspect of some embodiments of the present invention isthat the matrix-reinforcing material, prepared as above, possesses ahigh solubility in many common organic solvents, including alkanes,toluene, benzene, ketones, and alcohols. The latter are especiallyuseful in the present invention as alcohols such as ethanol and2-propanol are common solvents employed in the sol-gel syntheses ofporous oxides from alkoxide, or other, precursors. Consequently thesolid residue containing the matrix-reinforcing compound is dissolved inethanol, or another solvent for application to the porous solid matrix.

Optionally a coupling agent can be used that is not a liquid at ambienttemperatures and/or steps and components are selected so that apredetermined non-maximal number of coupling agents are added to eachfullerene core in a given structure that embodies the present invention.A coupling agent is selected that has a much higher solubility than aselected fullerene. The solvent is preferably chosen so that it has goodsolvating ability towards fullerenes. A preferred solvent according tothe present invention is toluene, however, other solvents, including,but not limited to, xylenes, carbon disulfide, 1,2-dichlorobenzene,1-methylnapthalene, or 1-chloronapthalene may be employed. To a solutionof fullerene in the selected solvent is added the amount of couplingagent corresponding to the number of arms desired on thematrix-reinforcing compound. The mixture is desirably held at elevatedtemperatures for at least about 24 hours, after which the solvent isremoved from the dark red-brown solution. As above the residue isredissolved in a solvent suitable for application to the porous solidmatrix, such as ethanol.

The porous solid matrix to be strengthened may consist of any of themany inorganic compositions known to form mesoporous networks. Commonexamples include, but are not limited to, SiO₂, TiO₂, ZrO₂, Al₂O₃, SnO₂,GeO₂, Y₂O₃, and mixed oxides such as SiO₂, TiO₂, and SiO₂, Al₂O₃.Non-oxide solids may also be used with the present invention providedthey possess a suitable structure. Preferably such solids are selectedso that they have an accessible mesoporous surface with a degree ofreactivity with one or more of the primary components described hereinthat is at least as large as that of SiO₂.

The above-described solution of the matrix-reinforcing compound is addedto the solution which will form the solid oxide network at a point intime when the primary particles have reached their expected size andbegun to link together, but have not yet completed the formation of athree-dimensional porous network, the latter time commonly referred toin the art as the gel point. This allows the matrix-reinforcing compoundto mix well with the porous solid precursor solution, but not tointerfere with the formation of the primary particles. When a molecularalkoxide is used as the precursor to the porous solid matrix, theappropriate time to add the solution of the matrix-reinforcing compoundto the porous solid precursor solution is approximately 60-80% of thegel time. This quantity varies for each specific precursor solution, butis a quantity easily determined by those skilled in the art. Whenprecursors are used which already possess well-formed primary particles,such as partially-hydrolyzed alkoxides, or colloidal sols, thematrix-reinforcing compound solution may be added to the porous solidprecursor solution at the beginning of the sol-gel process.

When forming the matrix reinforcing compound, the molar ratio of thecore material and the arm forming material may correspond to the numberof arms per core desired. For example, if about six arms per core aredesired, then the starting materials for the arms and the core may beadjusted to be in about a six to one molar ratio. In some embodiments,the molar ratio of the arm forming material to the core forming materialmay be from about 4 to 1 to about 7 to 1.

The amount of matrix-reinforcing compound required depends on the degreeof surface coverage desired. When the aim is to only add reinforcementto the necks between adjacent particles approximately 5-10% of the totalexposed surface needs to be covered. For a typical mesoporous silicamaterial, with a specific surface area of ˜800 m²/g, and amatrix-reinforcing compound of the type shown in FIG. 1, approximately80 mg of matrix-reinforcing compound are required for every gram ofsilica. If higher coverage is desired a correspondingly higher amount ofmatrix-reinforcing compound is used. A simple chain of solid particles,10, from a portion of an untreated porous network is represented in FIG.2A, while the effect of adding the matrix-reinforcing compound, 20, isshown in FIG. 2B. The arms of the matrix-reinforcing compound are shownas solid lines and bind the molecules to the solid surface, 10, and toadjacent molecules, significantly strengthening the structure. In someembodiments, the weight percent of the matrix reinforcing material tothe porous material may be from about 3-30%.

Embodiments of the present invention preferably cause reactions to becompleted more rapidly than Ostwald ripening processes, i.e. morerapidly than 4 to 6 days. This is attainable due to the much larger sizeof the matrix-reinforcing molecules compared to the material normallyredissolved by Ostwald ripening, such as silicic acid. Consequently,very few of the matrix-reinforcing molecules need to be transported toareas with negative curvatures in order to fill those areas and providethe desired reinforcement. For that reason, the reinforcement process ofthe present invention proceeds much more quickly than the standardOstwald ripening approach.

The reactive groups of the matrix-reinforcing material may be chosen soas to possess a rate of hydrolysis that is notably slower than thehydrolysis reactions the alkoxides which may be used in the formation ofthe porous solid matrix. This ensures that the matrix-reinforcingmolecules are generally not incorporated into the primary skeleton ofthe porous solid matrix, which would undermine the desired reinforcingeffect. The rate of hydrolysis of alkoxides is most easily modified bystearic factors of the group —OR, and by selection of a larger group forR, the rate of hydrolysis may be substantially reduced. An example ofthe relative rates of hydrolysis for several possible R groups, wellknown to those skilled in the art, is methyl>ethyl>t-butyl>benzyl.Therefore, in the present invention, if an alkoxide compound such asSi(OCH₃)₄ is used to form the porous solid matrix, —Si(O-t-C₄H₉)₃ may bechosen as the terminal reactive group of the matrix-reinforcingmolecules.

The matrix-reinforcing molecules are optionally added to the poroussolid matrix after the formation of said matrix has been completed. Incertain cases, where the solid matrix is strong enough to withstandrewetting, the matrix-reinforcing molecules may be introduced into apreviously-dried porous solid matrix, as a solution in an appropriatesolvent. However, such introduction of the matrix-reinforcing moleculesis preferably accomplished while the porous solid matrix still containsits original pore fluid. This can be easily accomplished by contactingthe fluid-filled porous solid matrix with a solution of thematrix-reinforcing molecules in a compatible solvent. The length of timeneeded for this process step is proportional to the thickness of theporous film, or the size of the porous body to be reinforced. Thisprocess does not possess the level of control of surface coverage shownby the previous aspect of the current invention and is therefore mostuseful when a high degree of surface coverage is desired. This may bedesirable when a modified surface chemistry is desired in addition tomechanical reinforcement.

A method embodiment of the current invention optionally includes athermal curing step to complete the bonding reactions of thematrix-reinforcing molecules with the solid surface and with adjacentmatrix-reinforcing molecules. Before this is performed the porous filmsor bodies reinforced according to the present invention are dried so asto remove substantially all of the pore fluid contained within. This isaccomplished by any of several means such as evaporation, solventsubstitution followed by evaporation, supercritical drying, solventsubstitution followed by supercritical drying or freeze-drying. Once thereinforced porous material has been completely dried, a final curingstep is performed. The parameters of this step are depended on thechoice of the terminal reactive group of the matrix-reinforcingmolecules. In the case where said group is a silicon alkoxide, or othermetal or metalloid alkoxide, the thermal cure serves to remove anyresidual —OR groups contained in the porous material, thereby enhancingthe bonding, and consequently the reinforcing effect, of thematrix-reinforcing molecules with the solid surface and adjacentmolecules. In a typical case when a silicon alkoxide is used as theterminal reactive group, the curing step involves heating the porousmaterial, under an atmosphere of moist air, to a temperature above 200°C., but not above 400° C. The methods described in this aspect, andprevious aspects of the current invention result in porous films orbodies with significantly enhanced mechanical properties relative tomaterials with a similar matrix composition and density.

EXAMPLE

The following non-limiting example demonstrates experimental conditionssuitable to prepare a porous film and/or body with improved mechanicalproperties according to the methods described hereinabove.

A mechanically strengthened porous silica material was preparedaccording to the processes of the present invention. A solution of apolyfunctional starburst-shaped fullerene molecule to be used as amatrix-reinforcing material was prepared as follows. 0.50 grams of C₆₀was mixed with 20 mL of 3-aminopropyltriethoxysilane in a 100-mL schlenkflask. The flask was flushed with dry nitrogen, and the mixture heatedto 60° C. for 24 hours. During that time the mixture slowly changed froma clear liquid containing a fine black suspended powder to a dark brownsolution with a moderate amount of a thick brown precipitate. Theremaining 3-aminopropyltriethoxysilane was removed by vacuumdistillation (b.p. 217° C. at 760 mm Hg) This should be accomplished atthe lowest possible pressure so that lower distillation temperatures maybe employed. After the brown-black residue was dry, a 0.250-gram portionwas removed and dissolved in 15 mL of ethanol. This solution wasfiltered to remove any undissolved material and reserved for use in thenext step.

15 mL of prehydrolyzed polyethoxysilane in ethanol (Silbond H-5, SilbondCorp.) was places in a 50 mL beaker and the solution prepared above wasadded slowly with rapid stirring. Such prehydrolyzed silica solutionstypically contain 20-25% silica by weight, and consist of polymers witha length scale of 0.5-5 nm, and typically form fine-structured, butrelatively weak, silica gels upon hydrolysis. Shortly after mixing 0.250mL of water in 5 mL of ethanol was carefully added to the sol. At thispoint the solution may be applied to a solid substrate by any of severalcommon methods for thin-film application, or poured into a mold forformation of a bulk porous body. In the latter case, the solutiontypically gelled after a further 30 to 120 seconds. The gel so formedwas covered and allowed to set for 18 hours. Subsequently, the hard,rigid, brown-black gel was removed from its mold and placed in a soakingsolution of 85% ethanol/15% water which had been brought to a pH of 9.0with aqueous ammonia, in order to complete the condensation of anyremaining polyethoxysilane. After 24 hours the soaking solution wasreplaced with 200-proof ethanol and the gel was allowed to soak for anadditional 18 hours. This step was repeated two more times.

At that point the gel was broken in half and one section allowed toslowly dry at ambient conditions giving a hard, dense xerogel afterapproximately 24 hours. The other piece was dried using CO₂ substitutionand supercritical drying according to standard procedures, to yield adark brown aerogel with a density of ˜0.20 g/cm³. Both of these piecesexhibited increased strength in both compression and tension, relativeto pure silica gels of similar density and prepared by similar methods.An optional thermal cure at 250° C. for 60 minutes enhanced the strengthof the gels still further.

As the fullerene-containing matrix-reinforcing material exhibits anintrinsically lower dielectric constant relative to SiO₂, the examplepresented here is especially useful when a strengthened porous silicafilm is desired for use as a low dielectric constant material formicroelectronics devices. For example, an electronic device may includea dielectric medium formed from a composite according to an embodimentof the invention. The composite may be on a substrate such as asemiconductor substrate. Conductive lines including a material such ascopper, aluminum, tungsten, etc. may be on the dielectric medium.

The invention is not to be construed as limited to the particularexample described herein, as this is illustrative rather thanrestrictive. The invention is intended to cover all processes andstructures that do not depart from the spirit and scope of theinvention.

1. A reinforced porous sol-gel material, prepared by a processcomprising: preparing a reinforcing material including one or morestructures, wherein each structure comprises a central core surroundedby one or more reactive arms; providing a porous sol-gel materialwherein a surface of the porous sol-gel material is chemically reactivetowards the reactive arms; applying the reinforcing material to thesurface of the porous sol-gel material; and bonding the reinforcingmaterial to the surface of the porous sol-gel material.
 2. Thereinforced porous sol-gel material of claim 1, wherein said preparingcomprises mixing a fullerene selected from the group consisting of C₆₀,C₇₀, C₇₂, C₇₄, C₇₆, C₇₈, C₈₄, C₉₆, and C₁₈₄ with at least one othermaterial.
 3. The reinforced porous sol-gel material of claim 1, whereinthe average number of reactive arms of each central core is between 3and
 20. 4. The method of claim 3, wherein the reactive arms of thereinforcing material comprise a first reactive group, a linear organicspacer; and a second reactive group.
 5. The reinforced porous sol-gelmaterial of claim 4, wherein the first reactive group is selected fromthe group consisting of primary amines, secondary amines, dienes,azides, and carbanions.
 6. The reinforced porous sol-gel material ofclaim 4, wherein the second reactive group is a metal-alkoxide ormetalloid-alkoxide.
 7. The reinforced porous sol-gel material of claim4, wherein the linear organic spacer is a linear alkane includingbetween about 3 and about 20 carbon atoms.
 8. The reinforced poroussol-gel material of claim 7, wherein the alkane includes one or moreinternal chain components selected from the group consisting of ethergroups, aryl groups, alkyne groups, alkene groups, amine groups, ketonegroups, and cyclic alkane groups.
 9. The reinforced porous sol-gelmaterial of claim 1, wherein the porous sol-gel material includes aplurality of pores with diameters between about 1 and about 50nanometers.
 10. The reinforced porous sol-gel material of claim 1,wherein the reinforcing material covers about 50-100% of the surface ofthe porous sol-gel material.